Individual monitoring systems and confinement systems have been developed for various applications. One application is the home confinement of early-release prisoners, which is a response by federal, state and local governments and agencies to overcrowded prisons and other social conditions. Another application is the confinement of an animal, such as a canine pet, to a property.
One type of monitoring and restraint system for such applications employs a receiver/transmitter that attaches to a subject, either human or animal, for determining whether the subject has left a confinement area. The confinement area is established by means of a permanent installation of a perimeter wire around the confinement area that is responsive to the receiver/transmitter. As a subject approaches the perimeter, the receiver/transmitter administers a deterrent to prevent the subject from leaving the area. One disadvantage of this system is that the installation of a perimeter wire is labor-intensive and therefore costly. Another disadvantage is that once the wire is installed underground, the confinement area is not easily changed. Relocating the system involves the additional labor and expenses required for the reinstallation of another perimeter wire in a new location.
Another type of system employs a centralized transmitter in combination with a receiver/transmitter. The receiver/transmitter notifies a central station when a subject moves outside the confinement area by transmitting a positional signal. The boundary is established by a relative signal strength level, where the farther the distance from the centralized transmitter, the weaker the signal. The signal strength is equated to the distance of the desired boundary from the transmitter. One disadvantage is that the transmitter may have blackout areas due to obstructions or interference with the signal and the position of the subject may therefore be lost. Another disadvantage is that the boundary configuration is typically limited to the concentric signal strength pattern, thus restricting the shape of the monitored boundary.